The Dirt Gardener's Column for June 12

Q. I've discovered there's nothing easier than growing radishes, though my recent crop sprouted within two weeks and now they are flowering! The foliage is very lush with tall stems but the radishes are very small, and thin. I've never had this happen before. Were the seeds planted too shallow or too deep?

A. The poor crop of radishes has nothing to do with how the seeds were planted. Improper planting would impact the seed germination, which in this case had no problems. The lush top growth with little or no root development is caused by excessive nitrogen in the soil. Radishes, carrots, beets, turnips, and other short-term crops, grow much to rapidly for the edible portion to form properly. The excessive nitrogen occurs from commercial fertilizers, and animal manures, in combination with organic matter/ soil amendments such as homemade compost or blended soil conditioners. The soil amendments are necessary with our clay soil as they help with drainage and soil compaction. The soil compaction is an important issue with root crops such as radishes, as they can be easily damaged when harvested. For a ten-foot by ten-foot area or one hundred square feet, one cubic feet of animal manure and four pounds of a Vegetable Food plus the soil amendments is sufficient. Many times the nutrients are over applied as the size of the garden is under estimated. It’s the, ‘if a little is good then a lot more is even better,’ mind set. In the area were root crops are planted, Superphosphate is often substituted for the animal manures. Superphosphate has no nitrogen but plenty of phosphorus for the underground development that of edible portion of the plant. This situation is easily corrected by adjusting the Nitrogen based nutrients at the time of planting. I wouldn’t hesitate in planting a new crop of radishes right away but I wouldn’t add any more nutrients. Nitrogen is a mobile element so it leaches out of the soil over time. If you have compaction concerns then add more amendments before sowing the seed.

Q. I have several old, established Oleanders that are top heavy, and not very attractive. I need to something with them. Is it too late to prune them back severely?

A. The ideal time to prune Oleanders is in the early spring before the flush of growth, however; it can be done now. Oleanders do recover from a severe pruning. It doesn’t matter whether it’s from a pair of pruning shears, loppers or a chain saw. Personally, I would cut the old growth off flush with the ground with a chain saw; instead of leaving the naked stems sticking up in the air. The new growth will come from the base of the plants and there may be some there already. You can encourage the new growth by fertilizing the plants with 16-16-16. Be sure to water the plants the day before and immediately afterwards to avoid any fertilizer burn problems.

by Buzz Bertolero, CCNP